The present invention relates to an air conditioner for a vehicle, which is used in a vehicle having, as a power source for driving the vehicle, an engine or both an engine and an electric motor.
In recent years, a hybrid car has been proposed in which an electric motor which electrically produces driving force is provided in addition to an engine which produces driving force by combusting fuel such as gasoline. In this hybrid car, even if the engine is stopped, the electric motor is driven by electric power supplied from a battery, which has been previously charged or which is charged by power generated by the engine during traveling, so as to drive the hybrid car.
On the other hand, even in an air conditioner provided in this type of hybrid car, it is necessary that a compressor be driven when air-conditioning the vehicle interior. For this reason, as disclosed in Japanese Patent Application Laid-Open (JP-A) No. 6-286459, the engine is started by operating a switch of an air conditioner when the engine is stopped, and a compressor is driven by the driving force of the engine.
As a result, a motor used only for driving a compressor of an air conditioner becomes unnecessary, and the air conditioner can be operated without using the driving force of an electric motor or the electric power of a battery to operate the electric motor.
However, in the above-described structure, it is necessary that the engine be started when operating the air conditioner. As a result, there exist drawbacks in that the driving force of the engine is used only for driving the compressor, which results in deterioration in fuel consumption, and the efficiency of utilization of power is also extremely low.
Accordingly, in view of the above-described circumstances, an object of the present invention is to provide an air conditioner for a vehicle, which allows air conditioning by efficiently utilizing the driving force of an engine or the driving force of an engine and an electric motor without providing driving means used only for driving a compressor.
The present invention is an air conditioner for a hybrid car, which is provided in a hybrid car equipped with an engine and an electric motor for running and which air conditions a vehicle interior by a refrigerating cycle formed to include a compressor and an evaporator and also by circulation of engine cooling water to heat dissipation means for heating, comprising: heat exchange means provided in the refrigerating cycle to cool water; heat storage means in which one of cooling heat of water cooled by said heat exchange means and heating heat of water heated by cooling the engine is accumulated; heat dissipation means for cooling, which cools air to be blown out into the vehicle interior by water to be supplied, as a refrigerant, from said heat storage means; a first circulating passage which circulates, to said heat storage means, engine cooling water circulated between the engine and said heat dissipation means for heating; a second circulating passage which circulates water, serving as a refrigerant, between said heat storage means, said heat dissipation means for cooling, and said heat exchange means; and switching means in which one of said first and second circulating passages is selected by switching and one of heat storage and heat dissipation for said heat storage means is carried out by water circulated through one of said first and second circulating passages.
As a result, when the engine is driven during cooling, the compressor is driven by the driving force of the engine to allow cooling. At this time, water is cooled by the refrigerating cycle and cooling heat of the water is accumulated in the heat storage means. Subsequently, while the engine is stopped or when the vehicle is being run by the driving of an electric motor, water is circulated from the heat storage means to the heat dissipation means for cooling so as to allow cooling of the air to be blown out into a vehicle interior.
Further, during heating, cooling water heated by the engine when being driven is used to allow heating, and the heat of the cooling water is accumulated in the heat storage means. Further, when the engine is stopped, water is circulated from the heat storage means to the heat dissipation means for heating so as to allow heating of the air to be blown out into the vehicle interior.
The switching means effects switching between storage of cooling heat and storage of heating heat by the heat storage means.
As a result, it is possible to heat and cool the vehicle interior without driving the compressor and it is not necessary that the engine be started to drive the compressor. For this reason, deterioration of fuel consumption can be prevented. Further, driving means such as a motor for driving the compressor while the engine is stopped becomes unnecessary.
By providing both the water cooling cycle and the water heating cycle, heating and cooling can be carried out according to a vehicle occupant""s preference. Further, it is also possible to heat the vehicle interior while carrying out dehumidification, without operating the compressor.
The determination as to whether the heat storage means is used as a heat source for heating or a heat source for cooling may be made in accordance with the operating state of the air conditioner or environmental conditions such as the outside air temperature, the vehicle-interior temperature, and the like. For example, when the cooling operation is carried out by the air conditioner, there is a high possibility of the cooling operation being continuously carried out. For this reason, the operation may be switched to the second circulating means so that the heat storage means serves as the heat source for cooling. Further, when the outside air temperature is low in the winter or the like, there is a high possibility the heating operation will be carried out, and therefore, the first circulating means may be used to allow the circulation of water (engine cooling water), serving as a refrigerant, to the heat storage means.
Meanwhile, not only the heat storage means, but the heat dissipation means for heating and the heat dissipation means for cooling may be used in common with each other. In this case, during heat storage, only the circulating means needs to be switched between heating and cooling, and at the time of heat dissipation (heating or cooling), water serving as a refrigerant only needs to be supplied from the heat storage means to the heat dissipation means. As a result, heating or cooling can be carried out in accordance with the heat accumulated in the heat storage means. Accordingly, the structures of the water cooling cycle and the water heating cycle can be simplified.
Further, the present invention is an air conditioner for a hybrid car, which is provided in a hybrid car equipped with an engine and an electric motor for running and which air conditions a vehicle interior by a refrigerating cycle formed to include a compressor and an evaporator, comprising: driving shafts provided respectively in the engine and in the electric motor; an output shaft connected to the driving shafts of the engine and the electric motor and rotated synchronously with a driving source which is one of the engine and the electric motor; load reduction means for reducing the driving load of said output shaft which rotates integrally with the driving shaft of the engine when the electric motor is driven; and driving force transmitting means which connects said output shaft and the driving shaft of the compressor to transmit the driving force of said output shaft to the compressor.
According to the above-described structure, when the electric motor is driven, a load for rotating the driving shaft of the engine connected to the output shaft of the electric motor is reduced by the driving load reduction means and the compressor is driven by remaining power.
In the present invention as described above, the above-described load reduction means is valve opening means for opening a valve while the engine is stopped.
Generally, when the driving shaft of the engine in a stopped state is rotated, air within a cylinder of the engine must be compressed, and therefore, a driving load is extremely high. Accordingly, in order to rotate the driving shaft of the engine, an extremely large driving force is required. On the other hand, so long as the driving load reduction means operates so as to, for example, open a valve which allows air supply and exhaust for a cylinder of the engine or open a throttle valve which opens and closes a passage of air to be supplied into the cylinder of the engine, compression of air within the cylinder of the engine or increase in air-intake resistance can be prevented, thereby allowing reduction of a load for rotating the driving shaft.
As described above, so long as the load for rotating the output shaft when the engine is stopped is reduced by the driving load reduction means, the compressor can be driven by using the driving force of the electric motor. In this case, in the same way as the aforementioned, it is not necessary to provide driving means used only for driving the compressor and it is also not necessary to start the engine to drive the compressor. For this reason, consumption of fuel caused by driving the engine can be restrained.
Moreover, the present invention is an air conditioner for a hybrid car, which is provided in a hybrid car equipped with an engine and an electric motor for running and which air conditions a vehicle interior by a refrigerating cycle formed to include a compressor and an evaporator, comprising: an auxiliary-machine motor which drives a plurality of auxiliary machines provided in the hybrid car; second driving force transmitting means which can transmit the driving force of the engine and the driving force of said auxiliary-machine motor to the plurality of auxiliary machines and also to the driving shaft of the compressor; driving force interrupting means which separates the driving shaft of the engine and said second driving force transmitting means from each other; and control means which separates the driving shaft of the engine and said second driving force transmitting means from each other by said driving force interrupting means when the engine is stopped and allows the plurality of auxiliary machines including the compressor to be driven by said auxiliary-machine motor.
As a result, when the engine is driven, the driving force of the engine is transmitted by the second driving force transmitting means to auxiliary machines including the compressor. Further, when the engine has been stopped, the driving shaft of the engine and the second driving force transmitting means are separated from each other by the driving force interrupting means and the compressor is driven by the driving force of the auxiliary-machine motor.
Accordingly, when the engine is stopped, the compressor can be driven by the auxiliary-machine motor in the same way as in other auxiliary machines provided in the hybrid car, and when the engine is being driven, the auxiliary machines including the compressor can be driven by the driving force of the engine.